class TreeNode:
    def __init__(self, val):
        self.val = val

    def set_left_child(self, node):
        self.left = node

    def set_right_child(self, node):
        self.right = node


def init():
    root = TreeNode(1)
    l = TreeNode(2)
    r = TreeNode(3)
    ll = TreeNode(4)
    lr = TreeNode(5)
    rl = TreeNode(6)
    rr = TreeNode(7)
    root.left = l
    root.right = r
    l.left = ll
    l.right = lr
    r.left = rl
    r.right = rr
    return root


root = init()
print()
